1. Field of the Invention
The present invention relates to a system for controlling the position of an inflatable bedrest placed under a mattress. More particularly, the invention relates to a system for controlling an inflatable bladder for use in raising and lowering a portion of a mattress at the head and/or feet of a user.
2. Description of Related Art
Adjustable beds have found widespread use beyond nonambulatory patients and are used in many homes among persons of all age groups, in particular beds that raise the head and/or feet. Among the devices used to raise the head or feet are inflatable air bladders intended for use with conventional beds. A number of patents disclose bladders for this purpose. For example, U.S. Pat. No. 3,392,412 to Aymar provides an inflatable bedrest placed under a mattress. The bedrest is in the form of a bellows filled with compressed air by a conventional electric motor having a casing mounted on legs with the bottom of the casing having an opening for the admission of air. Inside the casing there is an electric air compressor with a rotor having a shaft with blades. The air is compressed within the casing and passes through a valve located in the casing and then into a tube carrying the compressed air to the bellows. The user, lying on the bed, operates a switch to turn the motor on and off to inflate the bellows. The process may be reversed to deflate the bellows so that the compressed air will flow out through the casing.
Another adjustable bedrest is shown in U.S. Pat. No. 3,667,075 which discloses a bellows assembly placed under a mattress whereby the mattress is raised either at the head section or under the knees to different heights through the expandable bellows. The bellows assembly is activated by a motor containing position switches that are manually turned upwardly to actuate respective spool valves. When turned downwardly, the switches operate respective solenoid valves.
The Cammack patent, U.S. Pat. No. 4,309,783, discloses an inflatable bladder for raising or lowering different portions of a bed. The bladder includes flexible elements which extend from adjacent the apex to adjacent a sidewall designed to limit the expansion of the bladder. The bladder is coupled to a pump by an air hose. The pump is connected to a conventional electric outlet and by another cord to a control mechanism. The pump includes an overall housing that has a circumferential vent for communication with the external atmosphere. An annular air filter is disposed immediately inside the vent. Supported within the housing is an electric motor that drives a centrifugal blower. When activated, the blower draws air through the vent developing a positive pressure within the housing. The control mechanism has two double acting rocker buttons associated respectively with the valve outlets. Upon depression of a rocker button in one direction, the pump is energized at the same time that the valve outlet is opened allowing air to be delivered to the bladder. The same rocker button moved in the opposite direction enables air to be removed from the bladder.
U.S. Pat. No. 5,170,522 to Walker discloses an air adjustable bed having a foundation that has a first open top housing or recess located below a first transverse backrest plate. A first lift air bag is located in a first recess. When expanded, the first air bag has a generally triangular configuration to elevate the transverse backrest plate in a generally upward inclined position. A second air lift bag is located adjacent the leg portion of the structure in a second recess located below a second transverse backrest plate. When expanded, the second bag has a generally trapezoidal configuration. An air mattress is located on top of the foundation and the air mattress is adapted to bend with the transverse plates when the plates are elevated with the first and second lift air bags. A controller is used to control the operation of a pump to change the air pressure in the air bags. The controller has air operated switches for regulating a pump to supply air to air mattresses and lift air bags. Switches also control separate solenoid valves that are used to direct to the air mattress and lift bags.
U.S. Pat. No. 5,267,363 to Chaffee discloses a portable inflatable support system for inflating a mattress and in particular a dual valve assembly. The inflator is either battery powered or line-powered and is removably engaged with a pressure valve positioned in the mattress. In one embodiment, the inflator includes a dc motor powered by rechargeable batteries and an impeller driven by the motor, all mounted in a housing having a mouth region that is removably engaged with the inflation input of the dual valve. The inflator is connected directly to the mattress. The inflator is designed to cease delivering air to the mattress after a determined time has elapsed.
It is an object of the present invention to provide a compact, easy to use system for inflating a bladder used to lift a portion of a bed mattress that provides the necessary combination of pressure and volume of air to easily inflate the bladder.
Another object of the present invention is to provide a hand held controller with a microprocessor for controlling the inflation and deflation cycles of an inflatable bedrest.
A still further object is to provide an efficient multi-stage compressor assembly capable of providing the air pressure and volume needed to fill the bladder in a short period of time.
It is a further object of the present invention to provide a compressor that is capable of inflating a bedrest bladder and yet be sized so as to fit under the bed.
The above and other objects and advantages of the invention are achieved by the provision of a system including a novel inflatable bladder, a microprocessor based hand held controller for controlling inflation and deflation of the bladder and an improved multi-stage compressor assembly for supplying compressed air to the bladder. The system may be used with a conventional bed.
The bladder contains an interior baffle which is essentially is two sheets of material which extend for primarily the length of the bladder and are welded to interior walls of the bladder to form an inverse triangle inverse to the triangle formation of the bladder once it is inflated. The benefit of this interior baffle is that once the bladder is inflated, the baffle will cause the bladder to form into an appropriate triangular shape. Without this baffle, even though the overall structure of the bladder is intended to be triangular when it is inflated, the shape cannot be as precisely controlled without the baffle and the resultant bladder will form into possibly a circle or an oblong shaped object of non-triangular shape. The interior baffle wall therefore enables the structure to form more precisely into the desired triangular shape in order to perform a more effective position when inserted under the mattress in the head location of the bed.
The compressor assembly has several stages reducing the volume of air. The compressor assembly includes a housing having an air intake, a motor and a centrifugal blower for passing air into a valve assembly. The compressor assembly also includes controls for directing the motor and the valve assembly. When inflating, the air passes under pressure through the centrifugal blower, past the motor and through a check valve into the valve assembly and through air outlet that is connected to an air supply tube. In a preferred embodiment, the valve assembly is equipped with a solenoid operated relief valve for use when deflating the bladder.
The microprocessor based controller enables an individual to inflate or deflate either the bladder under the head area or the bladder under the knee area of the bed to any desired amount with a simple control. In addition, the microprocessor permits computer programming so that the portions of the mattress can be automatically raised and lowered to different levels during different periods of time. An additional feature is that one does not need to simply continue to hold the switch down to raise or lower the bladder but instead can press a simple button after the microprocessor has been preprogrammed so that any one of a number of different adjustments can be made and these can be made at any given time and preset to any given time and interval.
Thus, with the present invention there is provided a system for raising and lowering the head and or leg area of a bed that is easy to install, simple in operation and one that may be used with a conventional bed.